Heater-A/C Controls
HEATER AND AIR CONDITIONERAll vehicles are equipped with a common heater-A/C housing assembly. The system combines air conditioning, heating, and ventilation capabilities in a single unit housing mounted in the engine compartment, and a common air distribution duct system under the instrument panel. On heater-only systems the evaporator coil is omitted.
Outside fresh air enters the vehicle through the cowl top opening at the base of the windshield, and passes through a plenum to the right cowl side inlet. Air passes through the cowl side inlet into the heater-A/C recirculating air housing in the engine compartment. The recirculating air housing is also connected to a recirculation air intake opening in the dash panel. A vacuum-actuated recirculation air door controls whether fresh outside air or recirculated air enters the heater-A/C system. The selected air then passes into the blower housing. Air flow velocity can then be adjusted with the blower motor speed selector switch on the heater-A/C control panel. The air intake openings must be kept free of snow, ice, leaves, and other obstructions for the heater-A/C system to receive a sufficient volume of outside air.
The heater and optional air conditioner are blend-air type systems. In a blend-air system, a blend air door controls the amount of unconditioned air (or cooled air from the evaporator on models with air conditioning) flows through, or bypasses, the heater core. A temperature control lever on the heater-A/C control panel determines the discharge air temperature by moving a cable, which operates the blend-air door. The blend-air design allows an almost immediate manual control of the heating and air conditioning system output air temperature. The heater-A/C housing unit is mounted to the dash panel under the hood and on top of the blower housing.
The conditioned air is directed through the dash panel into the air distribution duct under the instrument panel. The mode control switch on the heater-A/C control panel is used to direct the conditioned air to the selected system outlets. The mode control switch uses engine vacuum to control the mode doors in the distribution duct, by operating vacuum actuator motors.
Both the heater-only and the heater-A/C units have a vent that uses a sliding door and grille arrangement in the left cowl side trim panel. This vent allows outside fresh air to flow directly into the vehicle.
REAR HEATER-ONLY
An optional rear heater is available and operates in conjunction with the front heater. The unit consists of a heater core and a three-speed blower motor enclosed in a housing. The assembly is mounted on the floor of the vehicle behind the driver seat. The unit recirculates and heats the air in the vehicle.
The rear heater plumbing is connected to the front heater plumbing. A vacuum-operated water valve is used to control engine coolant flow to the rear heater core through the rear heater plumbing. The rear heater water valve is opened when the temperature control lever is moved from the far left (Cool) position at least one-half inch toward the right (Warm) position.
REAR HEATER AND AIR CONDITIONER
An optional rear heater and air conditioner is available on models with the optional front air conditioner, and operates in conjunction with the front heater and air conditioner. The unit consists of a heater core, an evaporator, and an expansion valve. They are enclosed in a housing under the floor of the vehicle behind the driver seat. A three-speed blower motor and floor register are mounted on the floor inside the vehicle behind the driver seat, and an air distribution duct with various outlet locations (depending upon optional rear seating arrangement) is mounted behind the left rear side trim panel. The unit recirculates and conditions the air in the vehicle.
The rear heater plumbing is connected to the front heater plumbing. A vacuum-operated water valve is used to control engine coolant flow to the rear heater core through the rear heater plumbing. The rear heater water valve is opened when the temperature control lever is moved from the far left (Cool) position at least one-half inch toward the right (Warm) position.
The rear air conditioner plumbing is connected to the front air conditioner plumbing. A thermally-controlled expansion valve within the rear heater-air conditioner housing controls refrigerant flow at the rear evaporator.
HEATER AND AIR CONDITIONER CONTROLS
Both the heater and heater-A/C systems use a combination of mechanical, electrical, and vacuum controls. These controls provide the vehicle operator with a number of setting options to help control the climate and comfort within the vehicle. Refer to the owner's manual for more information on the suggested operation and use of these controls.
The heater-only or heater-A/C control panel is located in the instrument panel heater-A/C control bezel, inboard of the steering column. The control panel contains a sliding-type temperature control lever, a push button type mode control switch (four-button for heater-only, six-button for heater-A/C), and a toggle-type blower motor switch.
Models with the rear heater or rear heater-A/C option have an additional vacuum switch on the back of the heater-A/C control. This vacuum switch is used to control the auxiliary water valve, and the flow of engine coolant to the rear heater core. When the temperature control lever is moved from the far left or Cool position at least one-half inch or more toward the right or Warm position, the auxiliary water valve is opened.
Models with the rear heater or heater-A/C option also have a toggle-type rear blower motor switch mounted in the heater-A/C control bezel below the heater-A/C control panel. This switch controls the rear blower motor speed.